Piston-ring.



PatentedApril 12, 1904.

'lliairEn STATES PATENT OFFICE.

DONALD BARNS MORISOFLIOF HARTLEPOOL, ENGLAND.

ASPECIIEICA'I`IO1\T forming part of Letters Patent No. 757,214, datedApril 12, 1904.

Application filed February '7, 1903. Serial No. 142,394. (No model.)

To' all wlwm/ it may concern:

Be it known that I, DONALD BARNs MORI- soN, a subject of the King ofGreat Britain and Ireland, and a resident of Hartlepool, in the countyof Durham, England, have inventcertain new and useful Improvements inand Connected with Piston-Rings, of which the following is aspecification. I

It is found in practice, particularly with steam or gas of very highpressures, nthat the pressure acting on the inner circumference of.piston-rings causes excessive friction between the outer circumferenceof the piston-ring and the cylinder-walls and a consequent wearing awayof the material of the cylinder or the ring, or both. It is alsofound-that if a piston-ring tits a cylinder accurately very littlelateral pressure is necessary irl order to obtain the desiredsteam-tightness. i.

My invention relates to a device for limiting the expansion ofpiston-rings to a certain predetermined amount; and it consists ofv aApreferably fiat ring which is received within a recess in the `pistonring or. rings or partly in a recess in the ring and partly in thejunkvpiston-ring causes the outer surface of the ring to wear this wearcontinues only up to that point when the external diameter of theshoulder on the piston-ring is equal to the in- `terior diameter of thelimit-ring, and as the limit-ring causes the piston-ring to wearuniformly on its outer surface and tends also to lmaintain thecylindricity of the piston-ring itis found that the accuracy with whichlthe piston-ring fits the cylinder when the limit of vwear has beenreached is such that not only is the leakage of steam minimized, butthev friction between the ring and the cylinderwall isalso minimized,thereby increasing the further expansion of the piston-ring is desired,the limit-ring is removed and its inner diameter increased by filing orotherwise. In order to facilitate increasing the diameter, the innersurface of the limit-ring is reduced-as, for example', by means of agroove-so that the surface to be filed is lessened.- This' reductioni'ofthe surface is an important feature, as it re uces the time necessary tomake the adjustment. It is eyident that the adjustment may also beobtained by decreasing the diameter of the shoulder forming the recessvin the piston-ring.

Another feature of practical value in my invention is that facilitiesare afforded for obtaining exactly the adjustment required, as if thepiston-ring is placed within the cylinder and the amount of the openingat the division of the ring noted the piston-ring may then be removedfromthe cylinder and the inner diameter of the limit-ring so adjustedthat when the limit-ring is placed in the recess of the piston-ring theamount of opening at the divisionof the piston-ring can be accuratelymeasured and the'hn'iit of expansion determined.

'My invention is applicable to various forms and types of piston-rings,and' is also particu# larly suitable for the rings of piston-valves.

In the accompanying sheet of drawings, Figure 1 shows, .partly insection, a piston-ring and a limit-ring constructed in accordance withand embodying my invention. AFig 2 represents the said piston-ring vandlimit-ring as inserted into a piston. The piston-ring, limit-ring, andpart of the piston are shown in section. Fig. 3 is a lsimilar -sectionalview showing the piston illustrated in Fig. 2 placed within acylinder,for sake of simplicity only a part of the cylinder-wall being shown insecl tion. Fig. i is a sectional view of a piston provided withthree'piston-rings and three limit-rings, the piston-rings beingseparated. by suitable distance-rings.` Fig. 5 is a sectional view of apiston placed within a cylinder, the piston-ring being provided with twolimit-rings; and Fig. 6 is a similar view to Fig.

5. In this modification, however, the limitrings are placed partly'Within a recess of the roo piston-ring and partly within a Arecess ofthe piston-body or piston-cover, respect1vely.

Similar` letters of reference refer to slmilar parts throughout theseveral figures.

The piston-ring a, Fig. 1, is provided with a limit-.ring which isplaced within a. recess' a of the piston-ring. The limit-ring encirclingthe projecting lip or shoulder a2 of the piston-ring limits theexpansion of the pistonring to a predetermined amount.

The arrangement of piston-rings within pistons is well known and may beeffected in varions ways. If, for example, a piston consisting of a bodyL', Fig. 2, a cover (i, and a piston-ring ci, provided according to thisinvention with a limit-ring b, is placed within a cylinder w, Fig. 3,the cylinder-wall compresses the piston-ring inthe' manner shown in Fig.3. In' this position the exterior diameterof the shoulder` a2 is smallerthan the interior'diameter of the limit-ring I). The wear of the outercircumference of the piston-ring gradually reduces thisdiference untilthe lip or shoulder a2 of the expanding piston-ring bears upon theinterior rim or edge of the limitrin g. When the piston-ring hasexpanded into Y this position, the piston-ring held or secured `againstfurther expansion by its limit-ring fits the cylinderaccuratcly. This isof great practical importance, as a piston working as `it generally doesin high-pressure steam or gas is very liable to be adversely affected bythe consequent friction, the desired steam or gas tightness beingobtained at the same time by the said accurate or snug fitting of thepiston-ring. The modification illustrated in Fig. 4c shows a pluralityof piston-rings a, separated by distancerings-c and provided withlimit-rings b. Fig. 5 shows likewise a section of a piston, providedbetween its body and junk-ring or cover d with a piston-ringf, acteduponby` suitable springs e and encircled by two limitrings b. Thelimit-ring mayv also be placed partly within a recess of the piston-ringand partly in a recess of the piston, as will be seen in Fig. 6, inwhich the limit-rings arc each in a recess formed partly in thepiston-ring and partly in the body or cover respectively. .lnthis'cxample the piston-ring consists of two parts y, which areseparated by springs L.

.In order to facilitate increasing the diameter, the inner surface ofthe limit-ring is reduced by means of a groove b', so that the surfaceto-be filed is lessened. y

Having fully described, my'invention, what I claim, and desire to secureby Letters Pat#v flat faces and continuous rings encircling theshoulders` to limit the expansion of the split rings, substantially asand for the purposes set forth.' 1

4. The combination with apiston and its cover, of a piston-packingbetween them and an independent continuous ring of less diaml eter .thanthe bore of the cylinderfinto which the piston fits to surround aportion of the packing andlimit its expansion, substantially as setforth.

5. The combination with a piston and its.

cover, of a packing-ring having a lateral shoulder and a continuous rlnghaving a thickness about equal to the height of the shoulder, and

su'rroundingit;` and a groove cut in the inner circular face of the saidcontinuous ring, substantially as and for the purposes set forth.

G. The combination with a piston having a ,.body, a cover and' aperipheral groove, one

wall of which isforrned by the cover and the opposite wall in the body,oppositely-situated circular grooves in the opposite walls oftheperiphe'ralgroove in the piston, an eXpa-nsible packing in the groove insa'idpiston having grooves on its opposite faces anda continuous ringlying partly in a groove in the pack'- ing and partly in a grooveI in aside wall of -the peripheral groove of the piston, .substantially asdescribed. v

DONALD BARNS MORISON. Witnesses:

l. HARRY TILLY, Jr., .Jol-[N BfS'raovsR.

